(EP2098246)The purpose of the present invention is to elucidate a relationship between deregulation of signaling by CD22 and a rapid response of B cells by IgG-BCR and the like, and to provide a method capable of inducing a rapid immune response and defending against infection instead of vaccine. The present invention relates to a method for promoting an immune response causing such a strong proliferation of clones and production of a large amount of antibody-producing cells as those seen in the memory immune response even in the naive B cells expressing IgM-BCR and IgD-BCR by inhibiting The CD22 function in B cells; and to a method for screening a substance capable of promoting the immune response based on a change in the CD22 function in B cells.

特許請求の範囲（英語）

[claim1]1. An in vitro screening method for screening a substance capable of increasing proliferation and survival of B cells in an early stage of the immune response, wherein the method is based on determining the degree of inhibition of the expression of the CD22 gene in IgM and IgD positive naive B cells, wherein said method comprises the following steps: (a) contacting, in vitro, a substance to be screened with IgM and IgD positive naive B cells; (b) detecting the degree of inhibition of the expression of the CD22 gene in said cells; and (c) selecting a substance which inhibits said expression, and wherein the early stage of the immune response is from the first to the seventh day after an immunization.[claim2]2. A non-therapeutic method for screening a substance capable of increasing proliferation and survival of B cells in an early stage of the immune response, wherein the method is based on determining the degree of inhibition of the expression of the CD22 gene in IgM and IgD positive naive B cells, wherein said method comprises the following steps: (a) contacting a substance to be screened with IgM and IgD positive naive B cells; (b) detecting the degree of inhibition of the expression of the CD22 gene in said cells; and (c) selecting a substance which inhibits said expression, wherein the early stage of the immune response is from the first to the seventh day after an immunization, and wherein if said method is carried out in vivo, the subject is non-human.[claim3]3. A method according to Claim 1 or 2, wherein the early stage of the immune response is from the third to fifth day after an immunization.[claim4]4. A method according to Claim 1, 2 or 3, wherein increasing proliferation and survival of B cells comprises the increase of proliferation, division and/or survival of the B cells in the early stage of the immune response.[claim5]5. A method according to Claim 4, wherein the B cells proliferate and/or divide into IgG1 **+ B cells, IgM **+ B cells and germinal center B cells.[claim6]6. A method according to Claim 1, 2 or 3, wherein increasing proliferation and survival of B cells comprises class switching and/or differentiation of the B cells in an earlier stage.[claim7]7. A method according to Claim 6, wherein the class switching is that to IgG1 **+ positive cells and/or the differentiation is that into antibody-producing cells or germinal center B cells.[claim8]8. A method according to Claim 1, 2 or 3, wherein increasing proliferation and survival of B cells comprises an increase in the number of antibody-producing cells and in the amount of antibodies produced and/or the production of antibodies in an earlier stage.[claim9]9. A method according to any one of Claims 1 to 8, wherein the expression of the CD22 gene is repressed at a transcriptional level.[claim10]10. A method according to any one of Claims 1 to 8, wherein said inhibition is related to the promotion of signal transduction of B cell receptor.